CN215719166U - Fuel supply system and fuel supply assembly thereof - Google Patents

Abstract

A fuel supply system and a fuel supply assembly therefor are disclosed, the fuel supply assembly comprising a fuel supply pump (1) having an inlet connected to a fuel tank by an input line (L1) and an outlet connected to a high pressure assembly (5) by an output line (L2); a main filter (6) and a metering unit (8) arranged in the output line; and a throttle line (L6) connected at its upstream end to the output line downstream of the metering unit and at its downstream end leading to a tank; the throttle pipeline is provided with a throttle valve (10) capable of switching on and off states, the throttle valve is in an open state when the metering unit is closed or the pressure difference between the two sides of the metering unit is equal to or higher than a set value, and the throttle valve is in a closed state when the metering unit is open or the pressure difference between the two sides of the metering unit is lower than the set value.

Description

Fuel supply system and fuel supply assembly thereof

Technical Field

The present application relates to a fuel supply assembly for use in a fuel supply system. The application also relates to a fuel supply system comprising such a fuel supply assembly.

Background

Common rail fuel supply systems are often used in vehicles, machinery, fuel power plants, and the like. A typical common rail fuel supply system includes a supply pump, a high pressure assembly, and a common rail. The supply pump delivers pre-pressurized fuel through the metering unit to the high-pressure module, which pressurizes the fuel and then supplies the fuel at high pressure to the common rail, where the high-pressure fuel is injected into the engine. A main filter is arranged in the delivery line of the feed pump for filtering the fuel delivered by the feed pump. The downstream of the metering unit is connected with a throttle pipeline, and a throttle valve is arranged in the throttle pipeline and is mainly used for enabling fuel oil on the upstream side of the high-pressure assembly to return to the oil tank through the throttle pipeline in a zero-oil-supply state of the high-pressure assembly.

In this prior art solution, the return of the throttle line to the tank may, under certain operating conditions, result in inefficient supply of the high-pressure module to the common rail. Also, during the engine start phase, the high pressure components are poorly supplied with oil, which may result in poor engine starting capability.

SUMMERY OF THE UTILITY MODEL

The object of the present application is to solve the above-mentioned problems caused by the return effect of the throttle line in the fuel supply system of the prior art.

To this end, according to one aspect of the present application, there is provided an oil supply assembly including:

an inlet of the oil supply pump is connected to the oil tank through an input pipeline, and an outlet of the oil supply pump is connected to the high-pressure assembly through an output pipeline;

a main filter and a metering unit arranged in the output line; and

a throttle line, the upstream end of which is connected to the output line downstream of the metering unit and the downstream end of which opens into the oil tank;

the metering device is characterized in that a throttling valve capable of switching on and off states is arranged in the throttling pipeline, the throttling valve is in an open state when the metering unit is closed or the pressure difference between two sides of the metering unit is equal to or higher than a set pressure value, and the throttling valve is in a closed state when the metering unit is opened or the pressure difference between two sides of the metering unit is lower than the set pressure value.

In one embodiment, the throttle valve has two valve positions, wherein one valve position is a closed valve position and the other valve position is an open valve position.

In one embodiment, the throttle valve is a hydraulic control throttle valve, the valve position control oil pressure is a differential pressure across the metering unit, and the set pressure value is a cracking pressure of the throttle valve.

In one embodiment, the oil supply assembly further comprises a controller that controls operation of the oil supply assembly, the throttle valve being an electrically controlled throttle valve controlled by the controller.

In one embodiment, the controller is configured to control a valve position of the throttle valve based on a differential pressure across the metering unit, and the set pressure value is an opening pressure of the throttle valve.

In one embodiment, the controller is configured to synchronously control the operating state of the metering unit and the valve position of the throttle valve, wherein the metering unit is controlled to open and the throttle valve is placed in a closed valve position, or the metering unit is controlled to close and the throttle valve is placed in an open valve position.

In one embodiment, the throttle valve is a one-way throttle valve which in the open state allows fuel to flow in the throttle line in the direction from the outlet line to the tank, but prohibits fuel from flowing in the direction from the tank to the outlet line.

In one embodiment, the main filter is provided with a bleed air line for returning air released in the main filter to the oil tank via the bleed air line, in which a restriction is arranged.

In one embodiment, the oil supply assembly further comprises an exhaust gas particulate filter regeneration line connected to the output line between the main filter and the dosing unit.

The present application further provides a fuel supply system, comprising:

the oil supply assembly as described above; and

a high-pressure assembly connected to an output line of the fuel supply assembly and supplied with fuel through the output line.

According to the present application, the oil supply unit is provided with a throttle valve switchable between on and off states in a throttle line on the downstream side of the metering unit. The throttle valve is opened when the metering unit is closed or the differential pressure across the metering unit is high, and the throttle valve is closed when the metering unit is open or the differential pressure across the metering unit is low. Thus, during the engine starting phase, the throttle line is closed, so that no fuel flows back on the inlet side of the high-pressure assembly, and a greater amount of fuel is supplied to the high-pressure assembly than in the prior art, improving the engine starting capability. Under the steady operation or acceleration state of engine, throttle line is also closed, and the fuel feeding efficiency of high-pressure subassembly is high. In a state in which the metering unit is closed (for example, when the accelerator pedal is released to decelerate the engine), the throttle line is connected to effect a return flow of fuel on the inlet side of the high-pressure component, so that the operation of the engine corresponds to the intention of the driver or operator.

Drawings

The foregoing and other aspects of the present application will be more fully understood from the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic layout of a fuel supply system according to one embodiment of the present application; and

fig. 2 is a schematic layout of a fuel supply system according to another embodiment of the present application.

Detailed Description

FIG. 1 is a general configuration of a fuel supply system according to an embodiment of the present application. The fuel supply system is used to inject fuel, such as diesel fuel, into an engine (not shown).

The fuel supply system includes a fuel supply unit (low-pressure unit) including a mechanical fuel supply pump (low-pressure pump) 1 having an inlet connected to an input line L1 and an outlet connected to an output line L2.

An inlet line L1 extends to the tank 2, and a pre-filter (not shown) may be arranged in the inlet line L1. In addition, a manual pump (not shown) is connected to the input line L1 for manually pumping fuel into the fuel supply assembly to expel air from the fuel supply assembly when the fuel supply assembly is first installed or after servicing.

On both sides of the feed pump 1 a bypass valve 3 and an overpressure protection valve 4 can be arranged. The bypass valve 3 is used to let fuel pass over the feed pump 1 into the outlet line L2, for example in the case of manual pump operation. The overpressure protection valve 4 serves to return the fuel on the outlet side of the feed pump 1 to the inlet side.

The fuel supply assembly further comprises a return line L3 extending to the fuel tank 2 for returning fuel leaking from the various components of the fuel supply system back to the fuel tank 2.

The outlet line L2 leads to the high-pressure module 5 for supplying pre-pressurized fuel to the high-pressure module 5.

A main filter 6 for filtering contaminants in the fuel output from the supply pump 1 is disposed in the output line L2. The main filter 6 is provided with a bleed line L4 for returning air (and possibly some fuel) from the fuel released in the main filter 6 to the fuel tank 2 via the bleed line L4. A throttle 7 is arranged in the bleed line L4. For some types of main filters, especially down-in down-out type filters, a bleed line L4 is necessary.

Downstream of the main filter 6, a metering unit 8 is arranged in the outlet line L2. The metering unit 8 is typically of the normally open type, but the present application also covers solutions using a normally closed type metering unit. The metering unit 8 is opened at a predetermined opening to determine the amount of fuel delivered to the high-pressure component 5 via the output line L2.

The upstream end of the overflow line L5 is connected to the outlet line L2 between the main filter 6 and the metering unit 8, and the downstream end is connected to the return line L3. A spill valve 9 is arranged in the spill line L5 for discharging excess fuel in the output line L2 upstream of the metering unit 8 into the return line L3.

It should be noted that "upstream" and "downstream" are defined herein with reference to the flow of fuel in the various lines when the fuel supply system is in operation.

The throttle line L6 has an upstream end connected to the output line L2 between the metering unit 8 and the high-pressure module 5, and a downstream end connected to the relief line L5 downstream of the relief valve 9 or to the return line L3. A throttle valve 10 is arranged in the throttle line L6 for discharging excess fuel in the output line L2 downstream of the metering unit 8 into the return line L3.

The high-pressure module 5 is supplied with pre-pressurized fuel by the supply pump 1 via the outlet line L2. The high pressure assembly includes a plurality of plunger pumps 12 driven by a drive mechanism (e.g., a cam-type drive mechanism) 11. The intake port of each plunger pump 12 is connected to an output line L2, and the output port is connected to the common rail 13 via a high-pressure line L7.

The high-pressure assembly 5 is equipped with a leakage oil line or passage (not shown) which is connected to the input line L2 or the return line L3.

The common rail 13 is configured to supply fuel to a set of fuel injectors via fuel injection lines 14, which inject the fuel into an engine (not shown). The common rail 13 is equipped with a relief line L8, a relief and check valve 15 is disposed in the relief line L8, and a relief line L8 is connected to a return line L3.

Furthermore, in the output line L2, between the main filter 6 and the dosing unit 8, an exhaust gas particulate filter regeneration line L9 may also be connected, which particulate filter regeneration line L9 is intended to supply a certain amount of fuel to the exhaust gas aftertreatment system when the particulate filter of the engine exhaust gas aftertreatment system needs to be regenerated, so that combustion takes place in the exhaust gas aftertreatment system to raise the exhaust gas temperature to a temperature at which soot in the particulate filter is burned, enabling the particulate filter to be regenerated.

The throttle valve 10 has a switchable on-off state. According to the solution in fig. 1, the throttle valve 10 is a pilot operated two-position two-way valve having a normally closed position and an open position after activation. In the normal closed position, the throttle valve 10 is closed between the two ports. In the opened position after the start, the two ports of the throttle valve 10 are communicated with each other, so that the fuel can flow through the throttle valve 10. The throttle valve 10 may be further configured as a one-way throttle valve that, in an open state, allows fuel to flow through the throttle valve 10 in the direction from the output line L2 toward the return line L3 in the throttle line L6, but does not allow reverse flow. The first side control end of the throttle valve 10 is connected to the output line L2 on the upstream side of the metering unit 8, the second side control end is connected to the output line L2 on the downstream side of the metering unit 8, and the second side control end is further equipped with a return spring. When the differential pressure across the metering unit 8 (i.e., the oil pressure in the output line L2 on the upstream side of the metering unit 8 minus the oil pressure in the output line L2 on the downstream side of the metering unit 8) is lower than the opening pressure of the throttle valve 10, the net thrust generated by the oil pressures at the control ends on both sides is smaller than the thrust of the return spring, and the throttle valve 10 is in the normal closed valve position. When the pressure difference across the metering unit 8 is equal to or higher than the opening pressure of the throttle valve 10, the net thrust force generated by the oil pressure at the control ends is greater than the thrust force of the return spring, and the throttle valve 10 is switched to the opened position after activation.

The spool of the throttle valve 10 may be axially slidable or rotatable.

The operation of the fuel supply system shown in fig. 1 will be described.

When the feed pump 1 is actuated, it draws fuel from the fuel tank 2 through the input line L1 and discharges the fuel into the output line L2. The fuel in the outlet line L2 flows through and is filtered by the main filter 6. The filtered fuel is supplied to the high-pressure module 5 in a metered manner by the metering unit 8, and the excess portion of the filtered fuel overflows into the overflow line L5, flows through the overflow valve 9, then flows into the return line L3 and returns to the tank 2. The high pressure assembly 5 receives fuel from the output line L2, pressurizes the fuel to a high pressure by the plunger pump 12, and then supplies the high pressure fuel to the common rail 11 through a line L7. The high-pressure fuel in the common rail 11 can then be injected from the injector into the engine via the injection line 14.

In operation of the fuel supply system, when the differential pressure across the metering unit 8 is lower than the opening pressure of the throttle valve 10, the throttle valve 10 is in the closed position, and the fuel in the output line L2 on the downstream side of the metering unit 8 is not returned to the fuel tank 2 through the throttle line L6 and the return line L3. When the pressure difference across the metering unit 8 is equal to or higher than the opening pressure of the throttle valve 10, the throttle valve 10 is switched to the open valve position, allowing the fuel in the output line L2 on the downstream side of the metering unit 8 to flow back to the fuel tank 2 through the throttle line L6 and the return line L3.

As a specific example, in a state where the metering unit 8 is closed, for example, when the accelerator pedal is released to decelerate the engine, the supply of fuel to the high-pressure module 5 via the output line L2 is stopped (zero-fuel state), and a high pressure difference is generated across the metering unit 8, at which time the throttle valve 10 is opened to allow the fuel in the output line L2 on the downstream side of the metering unit 8 to flow back, thereby ensuring that the zero-fuel state is correctly achieved, so that the engine is decelerated as intended.

In a state where the metering unit 8 is partially opened or fully opened, for example, at the time of constant speed or acceleration of the engine, during the engine start, the differential pressure across the metering unit 8 is low, and the throttle valve 10 is closed to prohibit the backflow of the fuel in the output line L2 on the downstream side of the metering unit 8, thereby ensuring correct and reliable operation of the engine. Compared with the prior art (the throttle line is always in an open state), a larger amount of fuel is supplied to the high-pressure module 5, improving the fuel supply efficiency of the high-pressure module 5; further, the starting capability can be improved at the time of engine starting.

It is noted that in the case of a low pressure assembly provided with a particulate filter regeneration line L9, it may be necessary to supply a certain amount of fuel to the exhaust aftertreatment system via the particulate filter regeneration line L9 during engine operation to effect particulate filter regeneration. At this time, if the upstream side pressure of the metering unit 8 is low, the fuel pressure in the particulate filter regeneration line L9 may not reach the fuel amount and the fuel pressure required for the particulate filter regeneration. According to the solution of the present application, since the throttle valve 10 is closed when the differential pressure across the metering unit 8 is low, it is possible to ensure that the pressure on the upstream side of the metering unit 8 is high, and therefore the fuel pressure in the particulate filter regeneration line L9 is high, ensuring the amount of fuel and the fuel pressure required for the particulate filter regeneration.

Various modifications may be made to the details of the oil supply assembly described above by those skilled in the art.

For example, the throttle valve 10 described above is of a hydraulically controlled type, but the throttle valve 10 may also be of an electrically controlled type. Such an embodiment is illustrated in fig. 2.

As shown in fig. 2, the fuel supply system includes a controller 20 that controls the operations of the supply pump 1, the metering unit 8, the high-pressure assembly 5, and the like. The control end of the throttle valve 10 is provided with an electromagnet controlled by a controller 20. When the electromagnet is in a power-off state, the throttle valve 10 is kept at a normal valve position by the reset spring; after the electromagnet is electrified, the throttle valve 10 is switched to the start valve position by overcoming the thrust of the return spring. In this example, the normal valve position may be set as the closed valve position and the open valve position may be set as the open valve position, or the normal valve position may be set as the open valve position and the open valve position may be set as the closed valve position.

The controller 20 synchronously controls the on-off of the metering unit 8 and the valve position of the throttle valve 10. Specifically, the controller 20 controls the throttle valve 10 to close simultaneously when controlling the metering unit 8 to open (fully open, partially open); the controller 20 controls the throttle valve 10 to open at the same time as the metering unit 8 is controlled to close.

Other aspects of the embodiment of fig. 2 are the same as or similar to the embodiment of fig. 1 and will not be repeated here.

According to a modification of the embodiment in fig. 2, the metering unit 8 is provided with pressure sensors for detecting the oil pressure in the output line L2 on the upstream side and the downstream side, respectively, or the metering unit 8 is provided with a differential pressure sensor for detecting the differential pressure upstream and downstream thereof, the controller 20 determines the differential pressure across the metering unit 8 based on the detection results of the pressure sensors or the differential pressure sensor, and controls the valve position of the throttle valve 10 based on the differential pressure across the metering unit 8.

It should be noted that although the bleed line L4 is provided in the low pressure assembly in the various embodiments described above, the throttle valve 10 and its control scheme as described above may be employed in a low pressure assembly that is not equipped with the bleed line L4 to achieve similar technical effects. The scope of the application therefore also covers low-pressure assemblies which are not equipped with a bleed line L4.

Other modifications of the low pressure assembly may be envisaged by the skilled person.

Furthermore, the present application relates to a fuel supply system, in particular a diesel injection system of the common rail type, comprising the above-described fuel supply assembly.

In summary, the present application can obtain the following technical effects.

(1) The engine starting capability is improved.

(2) The oil supply efficiency of the high-pressure assembly is improved.

(3) When the particulate filter regeneration line is provided, it is possible to ensure that the regeneration fuel oil is supplied to the particulate filter regeneration line at a sufficient pressure.

Although the present application has been described herein with reference to particular embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.

Claims (10)

1. An oil supply assembly comprising:

an oil feed pump (1) having an inlet connected to the oil tank through an input line (L1) and an outlet connected to the high-pressure module (5) through an output line (L2);

a main filter (6) and a metering unit (8) arranged in the output line; and

a throttle line (L6) connected at its upstream end to the output line downstream of the metering unit and at its downstream end leading to a tank;

the metering device is characterized in that a throttling valve (10) capable of switching on and off states is arranged in the throttling pipeline, the throttling valve is in an open state when the metering unit is closed or the pressure difference between two sides of the metering unit is equal to or higher than a set pressure value, and the throttling valve is in a closed state when the metering unit is opened or the pressure difference between two sides of the metering unit is lower than the set pressure value.

2. The oil supply assembly of claim 1 wherein the throttle valve has two valve positions, one of which is a closed valve position and the other of which is an open valve position.

3. The oil supply assembly of claim 2 wherein the throttle valve is a pilot operated throttle valve, the pilot oil pressure is a differential pressure across the metering unit, and the set pressure value is a cracking pressure of the throttle valve.

4. The oil supply assembly of claim 2 further comprising a controller (20) that controls operation of the oil supply assembly, the throttle valve being an electronically controlled throttle valve controlled by the controller.

5. The oil supply assembly of claim 4, wherein the controller is configured to control a valve position of the throttle valve based on a differential pressure across the metering unit, and the set pressure value is a cracking pressure of the throttle valve.

6. The oil supply assembly of claim 4 wherein the controller is configured to synchronously control the operating state of the metering unit and the position of the throttle valve, wherein the metering unit is controlled to open and the throttle valve is placed in a closed position or the metering unit is controlled to close and the throttle valve is placed in an open position.

7. The fuel supply assembly of any one of claims 1 to 6 wherein the throttle valve is a one-way throttle valve which in an open condition allows fuel to flow in the throttle line in a direction from the outlet line to the tank but inhibits fuel flow in a direction from the tank to the outlet line.

8. Oil supply assembly according to any one of claims 1 to 6, characterized in that the main filter is provided with an air bleed line (L4) for returning air released in the main filter to the oil tank via the air bleed line, in which a restriction (7) is arranged.

9. The oil supply assembly according to any one of claims 1 to 6, further comprising an exhaust gas particulate filter regeneration line (L9) connected to the output line between the main filter and the metering unit.

10. A fuel supply system, comprising:

the oil supply assembly of any one of claims 1 to 9; and

a high-pressure assembly connected to an output line of the fuel supply assembly and supplied with fuel through the output line.

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